Compressional wave transmitting and receiving apparatus



7, 1945- BATCHELDER 2,380,931

COMPRESSIONAL WAVE TRANSMITTING AND RECEIVING APPARATUS Filed May 19, 1953 2 Sheets-Sheet I I 33 J F I INVENTOR.

F Z Laurence Barche/der BY gum/ M A RMEY Aug. 7, 1945.

COMPRESSIONAL WAVE TRANSMITTING AND RECEIVING APPARATUS Filed May 19, 1933 2 Sheets-Sheet 2 I W I" 52 I )I 6 32 N b 5/ 42 43 so INVENTOR.

Laurence Bare/welder ATTO | BATCHELDER 2,380,931

Patented Aug. 7, 1945 COMPBESSIONAL WAVE TRANSMITTING AND RECEIVING APPARATUS Laurence Batchelder. Cambridge, Mass., assignor t'o Submarine Signal Company, Boston, Mass., a corporation of Maine Application May 19, 1933, Serial No. 671,870 12 Claims. (Cl. 111- 386) The present invention relates to apparatus for producing compressional waves and is applicable for the production of such waves in air, water or in other media.

In the present invention the compressional waves produced are more particularly in the range of so-called supersonic frequencies, that is. frequencles which are beyond the audlbllity of the human ear, although to some extent the present invention is also applicable to the production of high-frequency compressional or sound waves which are situated in the upper part of the audibllity range of the human ear and Just beyond it.

Due to the fact that metals possess reat elasticity and that the wave lengths of high frequency compressional waves are very short in metals, it is difllcult to assume that the masses involved in compressional-wave apparatus of this type move as masses alone without partaking in the vibration of the vibrating elements.

In the prior art devices have been used in which a. radiating surface or area was very large as compared with the wave length of the sound to be propagated in the propagating medium and the radiating surface was vibrated at a plurality of points in order to produce a plane wave or a directed beam of sound or compressional waves. Such devices have been usefully employed both in so-calied piezo-electric oscillators and in 05011 lators of the magnetic type.

In supersonic oscillators of the piezo-electric type a mosaic of piezo-electric crystals are mounted between steel plates. The thickness of the plates together with that of the crystals are such as to establish a tuning in a direction perpendicular to the plate surface and each crystal, in fact, vibrates that part of the plate where it is attached. An examination 01 this type of osciliator indicates that the whole plate does not move with the same amplitude and that between the places where the crystals are applied the vibrational energy is sometimes quite small.

In other types of oscillators the same characteristics are found and while it is possible to produce some vibration over an entire plate, it has been found a fact that the vibration is more particularly produced opposite the laces where the vibrational energy is applied. This gives evidence of the fact that in high frequencies there is difllculty in making a plate act as a diaphragm and the tendency is for it simply to act as a transmitting medium.

In devices employing other than piezo-electric means, for instance, in oscillators of the magnetostrictive type, it is possible in use resonant tubes or rods for driving a sound diaphragm over iis surface in the same phase. The difllculty, however, of making the whole diaphragm or plate to which the rods are attached vibrate is also presout here, and it is usually observed that the vibration occurs more particularly at the points where the rods or tubes, producing the compressional wage energy, are attached.

I havealso observed that it is quite impossible to predict Just how such plates or diaphragms will vibrate and just what load either radiating or mass load should be considered as belonging to each operating unit. In fact it appears that rods or tubes similarly attached which beforehand had the same resonant frequencies may well after attaching have other resonant frequencies. This fact alone makes it difficult to obtain a uniform resonance of all the operating units and seriously handicaps and limits the available power output, since some units are operating on resonance while other units are on the resonant point. This condition also distorts the soundbeam since it is apt to destroy the uniform phase vibration of the entire vibrating surface.

In the present system which I have devised I have avoided many of these difflculties by constructing each unit as an independently operating unit and establishing the same resonance point for each so that they can all operate with the same amplitude in the same phase at the same frequency. In order to produce a fixed beam of compressional waves it is only necessary in the present system to have a sufllciently large number of independently operating units positioned or nested close together vibrating in the same phase in order to produce a plane wave whose width in the propagating medium will be many times the wave length of the sound or compressional wave produced.

When it is desired to produce a directive beam of sound or compressional waves whose dirmtion can be controlled or varied, this may be done by vibrating lines or groups of individually operating units with proper phase differences, it being preferable under such conditions to have the individually operating units relatively point source so that each point in the medium may have the right vibrational phase.

Without further describing the feature of the present invention, the invention will be described in connection with the drawing which show everal embodiments of the inventionv Fig. 1 shows a plan view of the compressional-wave producing means; Figv 2 shows a section on the line X-X of Fig. 1; Fig. 3 shows a modification of the construction shown in Fig. 2; Fig. 4 shows a further modification of the structure set forth in Fig. 2; Pic. 5 shows a modification of the details of constructlon of the vibrationai tube; Figs. 6 and 7 show mrther modifications of the detail shownin Fig. 5; andFig. 8 shows a face view of the nesting. oi the individual operating units in a modified form.

In Figs. 1 and 2 the construction of theoscil lator shows a heavy plate in in which theremay be made perforations or holes ll having conical shoulders I2. The plate it! has a great number of perforations in which are placed the-oscillating tubes 53. i3, i3, etc. as indicated in Fig. 1.

The construction or the operating unit including the oscillating tube i3 is shown more in detailin Fig. 5. The oscillating tube I! in Fig. 5 is pro- .vided with a cap 14 covering one end or the tube while the other end l6 of the tube is flared out conically to rest in the shoulder I! of the plate iii. A clamping plug 18 rests within the flared-out end IE or the tube. The plug IB, as indicated in Fig.5, has a center hole I] and two small conduits i8 and 18 through which the conductors 20 and 2| pass. Formed as a part of the clamping plug i6 is a rod 22 which has a cap. at the end oi it. The core 21 is preferably 01 magnetizable mate rial and m'ay be permanently magnetized as well as the cap 28. In thisconstruction it is sometimes preferable to make the center core of iron and the ends of cobalt or chrome steel drilling the holes 18 and 19 through the end portion or the core of iron. .About the core 22 is wound a. coil 28 to. which the alternating current of the desired frequency is supplied for generating the compressional waves. and a direct current excita-- tion also if desired although-two separate wind-' netization of the tube I3.

tube resonance, the mechanical vibrations will be greater at the edge of the cap l4 than in the center, whil in the case of diaphragm resonance, or resonance of the plate H, the vibrational efiect will be greater at the center of the diaphragm than at the edge where the head I l is attached to the tube.

In Fig. 6 a means is shown whereby the resonance of the cap 26 may be placed above that of the tube IS without increasing materially the mass of the cap. This may be accomplished, as indicated in Fig. 6, by cupping the inside of the cap 26 so that the par-ts oi the cap near the tube.

were stronger than the center of the cap. The combination shown in Fig. 6 produces a piston action of the can 26 and provides, because 01' its uniformly large amplitude of the whole plate 26, a larger radiating area to the propagating medium.

In Fig. 2 means are provided in addition to the means indicated in Fig. 5 for providing mag In Fig. 2 it will be noted that a coil 21 is provided which is clamped between a magnetizable plate 28 and the plate ill by means of a bolt 28; The magnetizabie plate 28 may extend over the whole surface of the oscillator and is provided, as indicated in Fig. l, with holes 30 concentric with the tubes IS. The flux generated in the coil 21 is impressed upon the tubes [3 between the holes 30 formed in the plate 28 and the clamping places at the shoulders ill of the plate iii. The flux in the tubes 21 is such as to aid the'flux due to the permanent magnetization of the core 22 or the direct current ings may be used. The coil 24 may in part be supplied with a magnetizing current in addition to, or in place of, permanently magnetizing the core 22. As indicated in Fig.5. the core 22 extends downward wlthinthe tube i3 and the cap 23 is positioned near the end of the tube 83 near the cap Hi. the siz'eof the head or cap 28 being such that its edge comes very close to the inner wall of the tube i8.

As indicated in Fig. ll the tube is and the clamping cap 53 are held clampecl' in place by excitation in the coil 21.

All parts of the plate 23 are substantially at the same magnetic potential and equal flux will now through each tube l3 increasing the normal flux carried by. the magnetostrictive tubes. this connection it may be remarked that the generation 0! mechanical vibrations in magnetostriction action is produced by a variation'in fiux density occurring in the magnetostrictive element and that the most favorable and efi'ectivc results are producedwhen the normal magnetization of the magnetostrictive material is at a desired fixed flux density. This density is obtained by polarizing the magnetostrlct-ive element either means oi the externally threaded nut 25 which is threaded into the plate ill. The tube I3 is made of magnetostrictive material such as-nickel or some other suitable material; and compresslonsi vibrations cre'produced by vibration of the tube i B which vibrates the can" at tbe'endoi the i-uoe.

The vawing flux necessary operate'the tube 1 3 is obtained through the coil 24 which in street provides two poles. one in they clamping cap 16 and the other in the head 23 ncarthe' 'unclamped end or the-tube 18. These two poles set up a, magnetic, mm. which passes longitudinally through the tube It] and the variation in this fiur:

about a normal yalue produces compressionali'orces on the. tube to generate the mechanical vibrations.

in Fla. 5 the cap is is at the same thickness as the tube i2 and it should be noted that the 511i and thickness oi the cap it may be 'such as to produce a resonance whiclrcoupld with ,the resonance oi the tube 13, produces the resozianc of the operating asst-em. Two points of resonance may be noted, the on point at which the tube" resonance predominates and the other p intt which the plate or head resonance of the cap it predominates. In one case, in the case of the with a permanent described above. 7 V

Between the hes-q: plate it and the plate 28, as indicated in Fig. 2, there is spirits or cover 2H which is preferably of hard rubber or some such material and serves not only to till the space between the plate i and the external plate 28. but also to furnish baiile for the cap id oi the tube. The plate i is provided with a flange 32 and this rests upon the heavy inertia seat 33 which may be riveted so the ship. as indicated in Fig.3, through the rivets 3|. As indicated in the figure the seal; 33 has an outwardly extendiug flange 3i: lining theopening magnet or an .electromagnet as in the. vessel, and the skin of the vessel 36 is' Joined to the flangefit through the weld 31 or in this'may enclose the back end of the 2,380,981 I5, l6, l1 and 18 coming from the individual coils.

As indicated in the modification shown in Fig.

4 the three coils 42, 43 and 44, which preferably are positioned in a vertical straight line as indicated in Fig. 1. are connected in series through the connecting wires 45 and 46, there being therefore only two leads 41 and 48 which are brought out to the terminal or connecting board 4|, In the modification shown in Fig. 4 the heavy plate 49, corresponding to the plate ID in Fig. 2, extends outwardly towards the skin of the vessel and no rubber plate, as shown in Fig. 2, is provided. The oscillating unit as indicated in this figure comprises a magnetostrictive tube element 50 having a cap at the sound radiating end which is larger than the tube itself. The sound radiating end 5| may be extended beyond the plate 49 and made hexagonal as shown in Fig. 8, so that the entire group of radiating elements may be nested together as indicated in that figure. The radiating element 5! is indicated as a flat plate. but, as indicated in Fig. 6, this may be strengthened in the vicinity of the junction of the tube so as to make the plate 5| vibrate as a unit or in the piston fashion.

The tube 50 at its upper end, as indicated in Fig. 4, is solid in the center, thus forming a rod 52 which is provided with a shoulder 53 and a thinner end cylindrical portion 54 threaded to receive the nut 55. As is evident from the draw ings, the tube 50 is held in place by being clamped to the plate 49. between the shoulder 53 and the nut 55, the solid portion of the element 52 being driven into the plate 49 in a forced fit so that the cylinder 52 and the plate 49 really form a single unitary mass. Conduits 56 may be provided in the plate 49 to receive the conductors for the coils 43, etc. It will be noted in Fig. that the plate 49 surrounds each coil 43, etc. and

provides a return path for the magnetic flux established in the coils 43. etc. The magnetic flux path is through the tube 50, through the plate 5|, through the mass 49 and returning in the solid cylinder 52. In this manner a very efficient magnetic path is provided for the magnetostrictive tube and the magnetic flux is concentrated chiefly in the space that the tube occupies.

A further modification of the operating unit is indicated in Fig. 7. Here the plate 51 which is of the same general structure as that shown in Fig. 2 is provided in the perforations corresponding to the perforations H in Fig. 2 with rectangular shoulders 58 on which the magnetostrictive tube 59 rests. The magnetostrictive tube 59 is provided at its upper end with a square shoulder 50 which corresponds and fits snugly on the shoulder 59 of the plate 5!. The internal electrical element in this case comprises a core 6| having at opposite ends caps 62 and 53. The cap 63. however, has an outwardly extending flange 54 of such size that it is adapted to rest upon the shoulder Gil of the magnetostrictive unit. The threaded clamping plug 55, similar to that shown in Fig. 2 and threading into the plate 51, is used to clamp the unit firmly in place. The magnetostrictive tube 51 may be capped with a cap 66 of the same type as indicated in Fig. 5 or it may have a piston type can as indicated by 26 in Fig. 6. A hard rubber plate 61. corresponding to the plate 3| in Fig. 2. may be provided to serve the same purpose as the plate 9| in Fig. 2 and form a continuous surface with the skin of the vessel.

It will be noted, in fact, in Figs. 1. 2 and 4 that the oscillator is formed as a continuous surface and may be made, as indicated in Fig. 4, continuous with the skin of the vessel 36. This is extremely important in preventing points of pressure release behind the operating unit and providing a. continuous rigid surface at the points of generation of the plane wave in order to insure that no distortion of the plane wave may exist through irregularities surrounding the vibrating surfaces.

As has been pointed out above, the radiating elements indicated in Fig. 4 may be hexagonal in shape and they also may take other shapes which are, suitable tb be nested together to form a continuously vibrating surface.

In the drawings shown in Fig. 8 the total dimensions 01' the vibrating system should be many times the wave length of the sound or compressional waves in the propagating medium and preferably the nesting, when it is desired to produce a fixed directive beam, should be such as to produce vibrational energy over the entire vibrating surface. When it is desired to produce a beam whose direction may be controlled, the individual units should be substantially a point source and for this reason it is preferable to have the effective dimension of the radiating sources small compared with a wave length. It is also preferable in such cases in order to prevent the secondary maxima from being objectionable and to have a beam which may be uniformly shifted, to have successive lines of units spaced at distances no greater than one-half wave length apart. It should be noted that for operating the system both as a fixed source and as an adjustable source the entire surface may be eflisiently used if the units are nested together in such a fashion that their dimensions are approximately one-hali' wave length and they are practically touching one another. From the discusslon above, however, it should be noted that the units should be independent and be independently operated in order that the phase. tuning and frequency might be accurately controlled.

In the modification shown in Fig. 3 which corresponds for the most part to the modification shown in Fig. 2 it should be noted that the magnetizable plate 28 extends beyond the cap of the tube' l3 providing a space around the end of the cap l3. This space may be covered with a cover 69 which preferably may be a soft rubber cover or similar material. The space 69 between the cover and the end of the tube l3 may be filled with some liquid, either water or castor oil, providing a transmitting medium between the radiating end of the tube and the propagating medium beyond the cover 68. Otherwise the construction shown in Fig. 3 is similar to that indicated in Fig. 2.

Having now described my invention, I claim:

1. Means for producing a beam of compressional waves comprising a heavy plate, a plurality of magnetostrictlve tubes having radiating caps at one end thereof, a magnetic core positioned within each of said tubes, said core having a winding thereon, means clamping the tubes in said plate and the cores in the tubes, a rubber diaphragm covering said tubes and solid means substantially filling the space between the tubes.

2. Means for producing a beam of compressional waves in water comprising a. plurality of spaced, independently operating magnetostrictive units having the some characteristics, liquid tight casing means holding said units in a unitary structure. each unit operating as an independent element therein, a watertight rubber diaphragm covering the radiating ends of said units exposed to the propagating medium, and liquid means carried within said casing surrounding said units. 3. Means for producing a beam of compressional waves in water comprising a plurality of spaced magnetostrictive units having similar characteristics, means surrounding said units to polarize the same, said units having radiating elements, means holding said units in a unitary structure having only one side exposed to the propagating medium and a watertight rubber diaphragm covering the radiating ends of said units positioned at said open side, each unit operating, as an independent element therein.

4. Means for producing a beam of compressional waves in water comprising a plate having perforations therein, a plurality of spaced radiating units having magnetostrictive means independently operating the same and mounted in and projecting from the perforations in said plate, means surrounding said units for polarizing the same, said means extending beyond said units forming a cavity over the units, a watertight covering extending over the means surrounding the units and forming with the plate a liquid tight casing and a liquid filling the space between the cover and the units.

5. In a means for producing a beam of compressional waves, a radiating unit adapted to vibrate at longitudinal resonance comprising a magnetostrictive tube having a cap thereon having the rim thicker than the center and means energizing the tube, positioned within it.

6. In a means for producing a beam of compressional waves, a radiating unit adapted to vibrate at longitudinal resonance. comprising a magnetostrictive tube having a cap thereon at one end and a shoulder at the other end, a plate in which said shoulder fits and means clamping said tube in said plate at said shoulder.

I. Means for producing a beam of compressional waves comprising a plate, a plurality of magnetostrictive tubes, means mounting and individually supporting said tubes in said plate close to one another and projecting to the surface of the plate to form substantially a continuous radiating plane surface, and electrical means for individually energizing each of said tubes in desired phase relation.

8. Means for producing a beam of compressional waves comprising a heavy plate having recessed portions therein positioned perpendicular to the surface of the plate, magnetostrictive tubes placed in said recessed portions, each having a cap thereon substantially filling the recessed opening in the plate, means clamping the tubes in said plate and a coil surrounding each tube positioned just below the cap on said tube.

9. In a means for producing compressional wave energy by the vibration of a plurality of similar units, a hollow magnetostrictive tube having a cap closing one endthereof a core positioned within said tube, said core comprising a stem portion and an end portion projecting towards the inner surface of the magnetostrictive tube near the cap end, a coil positioned about said stern portion for energizing said tube and means provided at the other end of the tube for holding said core and tube rigidly together.

10. In a means for producing a beam of compressional wave energy. a plurality Qif hollow magnetostrictive tubes each having one end closed by a cap element, a core positioned within each of said tubes, said core having a stem portion and an enlarged end portion projecting towards the side walls of the tube near the cap end, said core being provided at the other end with a flanged portion extending over the end of the tube and means for clamping said tube and core rigidly in place.

ii. In a vibratory mechanism, a plurality of magnetostrictive tubes each of which is closed at one end by a radiating cap, a heavy plate having recesses shaped to fit and surround said radiating caps, means mounting said tubes in said plate with the radiating cap flush therewith, and means associated with said tubes for imparting vibratory energy thereto or receiving vibratory energy therefrom.

12. In a vibratory mechanism, a plurality of magnetostrictive tubes each of which is closed at one end thereof by a radiating cap, said radiating cap having the shape of a regular polygon, a plate member having recesses adapted to receive said tubes, and means mounting said tubes in said recesses in said plate with the radiating cap flush therewith and means associated with said tubes for imparting vibratory energy thereto or receiving vibratory energy therefrom.

LAURENCE BATCHELDER. 

